/* Job-site practical: inputs on the left, the answer in a big panel on the right (below on phones), then the
   formula and tips. Concrete-grey paper, slate ink, safety-orange accent. System fonts only, no font requests. */
:root {
  --paper: #F3F4F6;
  --surface: #FFFFFF;
  --ink: #1F2933;
  --muted: #56616E;
  --line: #DADDE2;
  --accent: #C2410C;
  --accent-ink: #FFFFFF;
  --accent-soft: #FFEDD5;
  --answer: #1F2933;
  --answer-ink: #F8FAFC;
  --answer-muted: #B6C0CC;
  --warn: #9A3412;
  --warn-soft: #FFF1E6;
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI Variable Text", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-display: ui-sans-serif, system-ui, -apple-system, "Segoe UI Variable Display", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Mono", "Segoe UI Mono", Menlo, Consolas, monospace;
  --r: 8px;
  --col: 68rem;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #111418;
    --surface: #1A1F25;
    --ink: #E7EBF0;
    --muted: #A3ADB9;
    --line: #2C333C;
    --accent: #FB923C;
    --accent-ink: #1A0D03;
    --accent-soft: #3A2210;
    --answer: #0B0E11;
    --warn: #FDBA74;
    --warn-soft: #3A1F0D;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #111418;
  --surface: #1A1F25;
  --ink: #E7EBF0;
  --muted: #A3ADB9;
  --line: #2C333C;
  --accent: #FB923C;
  --accent-ink: #1A0D03;
  --accent-soft: #3A2210;
  --answer: #0B0E11;
  --warn: #FDBA74;
  --warn-soft: #3A1F0D;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 400 1.0625rem/1.65 var(--font-sans); }
a { color: var(--accent); text-underline-offset: 0.18em; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.wrap {
  max-width: calc(var(--col) + 32px);
  margin: 0 auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}

/* Header */
.top { background: var(--surface); border-bottom: 1px solid var(--line); }
.top .wrap { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 24px; padding-block: 12px; }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font: 800 1.08rem/1 var(--font-display); letter-spacing: -0.01em; }
.brand svg { flex: none; }
.nav { display: flex; flex-wrap: wrap; gap: 4px 18px; font-size: 0.95rem; }
.nav a { color: var(--muted); text-decoration: none; padding: 6px 0; }
.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] { color: var(--ink); font-weight: 650; box-shadow: inset 0 -2px 0 var(--accent); }

/* Hero */
.crumbs { margin: 20px 0 0; font-size: 0.88rem; color: var(--muted); }
.crumbs a { color: var(--muted); }
.hero { padding-block: 10px 18px; display: grid; gap: 8px; max-width: 46rem; }
.home .hero { padding-top: 36px; }
h1, h2, h3 { font-family: var(--font-display); text-wrap: balance; letter-spacing: -0.02em; }
h1 { margin: 0; font-size: clamp(1.9rem, 1.4rem + 2.2vw, 2.7rem); line-height: 1.1; font-weight: 800; }
.lede { margin: 0; color: var(--muted); font-size: 1.1rem; }

/* Calculator */
.calc { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 22rem); gap: 20px; align-items: start; padding-bottom: 8px; }
.inputs { display: grid; gap: 16px; padding: 18px; background: var(--surface); border: 1px solid var(--line); border-radius: 12px; }
.fields { display: grid; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); gap: 14px 16px; }
.field { display: grid; gap: 4px; align-content: start; }
.field > label, .legend { font-size: 0.88rem; color: var(--muted); font-weight: 550; }
input[type="number"], select {
  font: inherit; font-size: 1.05rem; width: 100%; min-height: 46px; padding: 8px 12px;
  border: 1px solid var(--line); border-radius: var(--r); background: var(--surface); color: var(--ink);
  font-variant-numeric: tabular-nums;
}
input[type="number"]:focus, select:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-soft); }
/* A number with its unit, and for feet an extra inches box, drawn as one field */
.unit { display: flex; border: 1px solid var(--line); border-radius: var(--r); background: var(--surface); overflow: hidden; }
.unit:focus-within { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.unit input, .unit select { border: 0; border-radius: 0; box-shadow: none !important; }
.unit input { min-width: 0; flex: 1; }
.unit > input { min-width: 4.5rem; }
.unit select, .unit .suffix { flex: none; width: auto; border-left: 1px solid var(--line); background: var(--paper); }
.unit select { font-size: 0.95rem; padding-right: 26px; }
.unit .suffix { display: inline-flex; align-items: center; padding: 0 10px; color: var(--muted); font-size: 0.92rem; white-space: nowrap; }
.unit .inch { display: flex; flex: none; border-left: 1px solid var(--line); }
.unit .inch input { width: 3.6rem; flex: none; padding: 8px; }
.check { display: flex; align-items: center; gap: 8px; font-size: 0.98rem; cursor: pointer; }
.check input { width: 20px; height: 20px; accent-color: var(--accent); }
.group { display: grid; gap: 14px; }
.extra { border-top: 1px dashed var(--line); padding-top: 12px; }
.extra summary { cursor: pointer; color: var(--accent); font-weight: 600; font-size: 0.95rem; }
.extra[open] summary { margin-bottom: 12px; }
.area-row { display: grid; gap: 10px; padding: 12px; border: 1px solid var(--line); border-radius: var(--r); background: var(--paper); }
.area-row .head { display: flex; justify-content: space-between; align-items: center; font-weight: 650; }
.btn {
  font: inherit; font-weight: 650; font-size: 0.95rem; cursor: pointer;
  min-height: 42px; padding: 8px 14px; border-radius: var(--r);
  border: 1px solid var(--line); background: var(--surface); color: var(--ink);
}
.btn:hover { border-color: var(--ink); }
.btn.link { border: 0; background: none; color: var(--muted); min-height: 0; padding: 4px 6px; }

.answer { position: sticky; top: 12px; padding: 20px; border-radius: 12px; background: var(--answer); color: var(--answer-ink); min-width: 0; }
.answer h2 { margin: 0 0 6px; font-size: 0.8rem; font-family: var(--font-mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--answer-muted); font-weight: 600; }
.answer .big { margin: 0; font: 800 clamp(1.8rem, 1.4rem + 1.5vw, 2.3rem)/1.1 var(--font-display); letter-spacing: -0.02em; font-variant-numeric: tabular-nums; }
.answer .sub { margin: 6px 0 0; color: var(--answer-muted); font-size: 1rem; }
.answer .rows { margin: 16px 0 0; display: grid; gap: 0; }
.answer .rows div { display: flex; justify-content: space-between; gap: 12px; padding: 8px 0; border-top: 1px solid rgba(255, 255, 255, 0.12); }
.answer dt { color: var(--answer-muted); }
.answer dd { margin: 0; font-weight: 650; text-align: right; font-variant-numeric: tabular-nums; }
.answer .note { margin: 12px 0 0; font-size: 0.86rem; color: var(--answer-muted); }
.tools { display: flex; gap: 8px; margin-top: 16px; }
.tool {
  flex: 1; font: inherit; font-weight: 650; font-size: 0.92rem; cursor: pointer; min-height: 40px;
  border-radius: var(--r); border: 1px solid rgba(255, 255, 255, 0.22); background: rgba(255, 255, 255, 0.06); color: var(--answer-ink);
}
.tool:hover { background: rgba(255, 255, 255, 0.14); }
.toast { margin: 10px 0 0; font-size: 0.88rem; color: var(--answer-ink); }
.saved { margin: 20px 0 0; padding: 16px 18px; background: var(--surface); border: 1px solid var(--line); border-radius: 12px; }
.saved h2 { margin: 0 0 8px; font-size: 1.05rem; }
.saved-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 6px; }
.saved-list li { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 8px 0; border-top: 1px solid var(--line); }
.saved-list li:first-child { border-top: 0; }
.saved-list a { display: grid; gap: 2px; text-decoration: none; color: var(--ink); min-width: 0; }
.saved-list a b { font-variant-numeric: tabular-nums; }
.saved-list a span { color: var(--muted); font-size: 0.88rem; }
.diagram { margin: 6px 0 0; max-width: 30rem; color: var(--ink); }
.diagram svg { width: 100%; height: auto; display: block; }
.diagram text { fill: currentColor; font: 500 13px var(--font-sans); }
.diagram figcaption { margin-top: 6px; color: var(--muted); font-size: 0.9rem; }
caption { caption-side: bottom; text-align: left; padding-top: 6px; color: var(--muted); font-size: 0.86rem; }
.sources p { color: var(--muted); font-size: 0.95rem; }
.answer .warn { margin: 12px 0 0; padding: 10px 12px; border-radius: var(--r); background: var(--warn-soft); color: var(--warn); font-size: 0.92rem; font-weight: 600; }

/* Article */
.content { padding-block: 36px 24px; display: grid; gap: 34px; }
.content section { display: grid; gap: 10px; max-width: 44rem; }
.content h2 { margin: 0; font-size: clamp(1.35rem, 1.15rem + 0.8vw, 1.65rem); line-height: 1.2; font-weight: 780; }
.content h3 { margin: 6px 0 0; font-size: 1.08rem; line-height: 1.3; }
.content p, .content ul, .content ol { margin: 0; }
.content ul, .content ol { padding-left: 1.3em; display: grid; gap: 6px; }
.formula { margin: 0; padding: 14px 16px; background: var(--surface); border: 1px solid var(--line); border-left: 4px solid var(--accent); border-radius: 0 var(--r) var(--r) 0; font: 500 0.98rem/1.6 var(--font-mono); white-space: pre-wrap; overflow-wrap: anywhere; }
.table-wrap { overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: 0.95rem; font-variant-numeric: tabular-nums; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-weight: 650; }
.faq { display: grid; gap: 8px; }
.faq details { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 12px 16px; }
.faq summary { cursor: pointer; font-weight: 650; }
.faq details p { margin: 8px 0 0; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); gap: 10px; max-width: none !important; }
.card { display: grid; gap: 4px; padding: 14px 16px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); color: var(--ink); text-decoration: none; }
.card:hover { border-color: var(--accent); }
.card b { font-family: var(--font-display); }
.card span { color: var(--muted); font-size: 0.92rem; }
.cat { display: grid; gap: 10px; }
.cat h2 { font-size: 1.15rem !important; }

/* Footer */
.foot { margin-top: 32px; border-top: 1px solid var(--line); }
.foot .wrap { padding-block: 24px 32px; display: grid; gap: 10px; color: var(--muted); font-size: 0.88rem; }
.foot p { margin: 0; }
.foot .groups { display: grid; grid-template-columns: repeat(auto-fit, minmax(10rem, 1fr)); gap: 18px 24px; padding-bottom: 10px; }
.foot h3 { margin: 0 0 8px; color: var(--ink); font: 600 0.74rem/1.3 var(--font-mono); letter-spacing: 0.08em; text-transform: uppercase; }
.foot ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 5px; }
.foot a { color: var(--muted); text-decoration: none; }
.foot a:hover { color: var(--ink); text-decoration: underline; }

@media (max-width: 860px) {
  .calc { grid-template-columns: minmax(0, 1fr); }
  .answer { position: static; }
}
/* Print: the inputs and the answer, on white, to take to the store */
@media print {
  .top, .foot, .content, .crumbs, .tools, .toast, .saved, .lede, #add-area, .btn.link, .extra:not([open]) { display: none !important; }
  body { background: #fff; color: #000; }
  .calc { display: block; }
  .inputs, .answer { border: 1px solid #999; background: #fff !important; color: #000 !important; position: static; margin-bottom: 12px; }
  .answer h2, .answer .sub, .answer dt, .answer .note { color: #333 !important; }
  .answer .rows div { border-top-color: #ccc; }
  .unit select { appearance: none; padding-right: 10px; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}